$screen-xs-max: 767px;
$screen-sm-min: 768px;
$screen-md-min: 992px;
$screen-lg-min: 1200px;

@mixin screen-xs() {
  @media all and (max-width: $screen-xs-max) {
    @content;
  }
}

@mixin screen-sm() {
  @media all and (min-width: $screen-sm-min) {
    @content;
  }
}

@mixin screen-md() {
  @media all and (min-width: $screen-md-min) {
    @content;
  }
}

@mixin screen-lg() {
  @media all and (min-width: $screen-lg-min) {
    @content;
  }
}
